Pre-bend closure die



PRE-BEND CLOSURE DIE Filed Dec, 2, 1964 2 Sheets-Sheet 2 United States Patent Office 3,335,72@ Patented Aug'. 22, 1967 3,336,729 PRE-BEND CLSURE D113 George Henry Logemann, Mondstein, Iii., assigner to Ekco Containers, Inc., a corporation of iiinois Filed Dee. 2, 1964, Ser. No. 415,462 1f) Claims. (Cl. 53--366) This invention relates to closure dies of the general type which are intended .to secure a lid or cover to a shallow metal foil container by bending and crimping the upper edges of the container about the border of the lid.

Metal foil containers of the aforesaid character are exemplified in Blane Patent 2,960,255, issued Nov. 15, 1960, and in the usual case, comprise a continuous outwardly projecting laterally disposed flange or ledge about the upper edge of the side walls of the container. The ledge provides an engaging surface for the peripheral portion of a complemental cover which is positioned theren upon filling of the container.

A continuous upstanding lip is also provided about the outer edge of the ledge or flange. The lip is intended to be bent or crimped inwardly by a closure die, inwardly over the upper face of the peripheral edge of the cover and crimped so as to clamp the cover in sealing relation and between the edge, so bent, and the ledge.

Packages of this general character enjoy an ever widening field of use, such las in packaging frozen foods for storage or distribution. An example of a typical use in the bakery industry is the packaging of coffee cakes and other pastries in such containers which may first serve as a baking pan, and subsequently as a container for distribution and sale.

The present invention will be better understood by briefly referring to the nature of the construction and manufacture of the metal foil pans 'of the type to which the present invention applies. Such pans or containers are usually formed from a one-piece Vblank using appropriate forming dies. Since it is desirable to have a one-piece container to minimize the total number of seams which must be contended with, the blank must be so constructed as to provide sufficient metal for one piece construction. As a result, the rounded corners of the container usually contain an excess of metal foil which is gathered in wrinkles at the corners. It has been found that the particular alignment of the aforesaid Wrinkles, at the corner sections, add to the strength of the closure portions, viz, the ledge and associated lip container. Comparison of the relative compressive strength of the upstanding lip which is to be crimped by the closure die at the corner area is significantly greater than that which parallels the liat sidewalls of the container.

In contrast, the upstanding lip portions disposed along the straight sides of the container are relatively weak from the standpoint of compressive strength and are thus more susceptible to undesirable bending by conventional forming and closing dies. In order to eliminate sharp edges along these sides, the peripheral edge of the lip is preferably rolled or curled. In accomplishing this, it sometimes happens that the upstanding lip is bent outwardly from its desired vertical plane. Thus, when the closure dies of the types heretofore known are employed, the die will on occasion crush or reverse bend a part of all of one or more of the upstanding lips on the sides of the container. The result, of course, is an imperfect and unattractive closure of the container. Ac-cordingly, it is an object of the present invention to provide an improved closure die which will assure proper bending and crimping of the upstanding lip portions paralleling the side walls of a metal foil container, thereby providing repeatable satisfactory sealing in these specific areas at all times.

More particularly, it is an objective of the present invention to provide an improved closure die arrangement suitable for providing adequate bending and crimping forces at the respective corners of the foil container while at the same time assuring proper sealing by bending and crimping of the upstanding lip portions paralleling the side walls of the container itself, thereby providing a perfect continuous seal on each container.

The foregoing, and other features and advantages of the present invention will become apparent upon reading the following detailed description of the invention taken in conjunction with the drawings, wherein;

FIGURE 1 is a perspective view of a typical rectangular shallow metal foil container, illustrating va portion of a suitable cover or lid fitted to the container upon filling;

FIGURE 2 is a plan view of a closure die constructed in accordance with the present invention, and partially fragmented in order to better illustrate particular features thereof in greater detail;

FIGURES 3, 3(11) and 3(b) are enlarged fragmentary sections of the side wall of the container of FIGURE l, and illustrating a portion of a closure die constructed in accordance with the present invention, and showing the same in various positions during the sequence of its operation;

FIGURE 4 is an enlarged fragmentary section of the container of FIGURE 1 taken inr a corner area, and illustrating an adjacent portion of the closure die constructed in accordance with the present invention.

While the features of the present invention are shown, and will be described hereinafter with respect to a generally rectangular shallow foil container, it will be appreciated that such showing is by way of exemplification, and not by way of limitation, and that it is the intention to cover all ramifications and modifications falling within t-he scope of the appended claims which define the invention.

Referring now, more particularly, to the drawings, and to the exemplary container of FIGURE 1, an exemplary package, identified at 10, is provided and comprises a shallow, generally rectangular, metal foil pan or container 12 and a closure member such as a cover or lid 14. The container 12 is formed from a single blank, and has a generally rectangular bottom wall 16 with outwardly sloping side and end wall portions 18 extending upwardly from the bottom wall. Because the container is formed from a one-piece blank, adjacent ends of the fiat wall 18 are joined by corner wall portions 19, which, by virtue of the forming die configuration, are rounded. In the production of the rounded corner walls 19, the foil whi-ch is excessive in area at the corners of the blank, is formed into folds or wrinkles extending generally in a vertical direction.

Formed integrally with each of the walls 18 and 19 is a lateral outwardly projecting land or ledge designated 11S and 119, respectively, to indicate the type of (side or corner end) wall from which each such fiat eminates. The lands are formed in a common plane parallel to the bottom wall 16, and together provide a continuous peripheral sealing ledge upon which the bordering edge portion of the cover member 14 may be initially placed as shown in FIGS. l and 3.

So as to provide adequate means for clamping and sealing the cover in place, a continuous upstanding lip structure formed integrally with the flats 118, 119 surrounds, and extends a suitable distance above the edge of the cover 14 on the lands. The aforesaid lip structure is comprised of flat rectilinear lip portions 218 disposed along the straight sides of the container, and by lips 219 which conform to the curved and thickened, wrinkled structure of the curved corner Walls 19.

The flat straight lips 113, are preferably outwardly rolled or curled as at 318 on the upper edges to avoid nuisance injuries resulting from handling sharp edged containers. The upper limit of the rounded lips 219 is somewhat below the highest level of the curls 318, as will be evident in FIGURE l.

Filled containers are closed and sealed by means of an appropriate closure die. An exemplary die of the type to which the present invention relates is illustrated in Logemann et al. Patent No. 3,064,407. The closure die assembly is a two-part die having a support portion and a closure portion. With reference to FIGURE 3, a support member 40 is provided, including a lateral support ring 42 adapted to engage the underside of the lands 118 and 119 and an upper, two part, sealing die member is also provided, indicated generally at 45, and comprising a ring member 47 and a corner plate 4S.

In accordance with the invention, the sealing die portion is so constructed as to provide satisfactory sealing of all surfaces irrespective of material thickness and compressive strength, and. possible slight reverse bending of the upstanding lips. To this end, and in order to eliminate crushing or otherwise imperfect bending of the side Wall lips 318, means are provided to cause an initial inward bend or tilt of the lips 31S so that as the crimping surface advances against the lips the die forces throughout the cycle, which normally act vertically will initially act, not vertically downward on the thin edge of the lip, but against the same in a direction to provide a pre-bend in the proper direction so that the die will therefore function properly in completing the cycle to bring about the desired seal.

In accomplishing the invention, an initial pre-bend in the proper direction is brought about by (in the present case, two) vertically retractible spring biased plungers or buttons 50 which are provided in appropriately spaced relation, along each of the straight sides of the die ring 47. Preferably these plungers are located in a symmetrical relationship adjacent the ends of the straight edged lips. The plungers are so constructed that upon initial engagement with the lip, they first impart an inward bending force to the edge of each of the side and end lips. Further in keeping with the invention, the plungers are mounted so as to retract to a position where the surface of the die ring comes into play to accomplish final bending and sealing of the side lips.

As illustrated, the exemplary plungers 50 are conveniently circular in cross section and are mounted in suitable guide bores 51 formed in the carrier plate 48. Within the bore 51 each plunger 50 is provided with a compression coil spring 53. The bore terminates in a land against which the spring is placed. The other end of the spring, of course, acts against the rear wall of the plunger to continuously bias the same in a downward direction.

The plungers have limited travel in the direction of the spring bias, and are restricted by means of an appropriately formed semi-open housing indicated at 55 in the die ring 47. The receptacle conforms to the nose of the plunger, and has an open area so as to permit engagement of the plunger and upstanding lip of the container.

In order to direct the plunger force at the desired angle from the vertical plane against the edge of the lips, the lower end or nose of each is formed into a cam section 60. For ease of manufacture the profile of the surface is conical, but any suitable camming surface will suffice. The location of the plungers 50 is preferably such that the apex of the cam section is outside the container so that an inclined side of the can is always located in the path of the upstandng curled edge of the related side or end lip 21S, even if such lip has an outward bend instead of being straight up. The forward wall of the die ring 47 will assure that any reverse bend is not excessive before the plungers make Contact. The plungers themselves are conveniently nestled in their respective housings so that only the proper earn surface can engage the curled lip. Also, the forward advance of the plunger or button 50 against the action of the spring 53 is limited.

As it has been pointed out, the present invention relates to a provision of a pre-bend in the upstanding lips of the container. Thus, in operation, the support and closure portions of the die are moved toward one another with the container resting upon the support portion 40, and particularly the ring 42 thereof and a cover 14 having been disposed on the flats 118, 119 of the container. It will be appreciated that either one or both of the die members may be moved, but in the present instance, the lower support die portion is moved and the upper portion remains xed and stationary.

With reference particularly to FIGURES 3, 3A and 3B of the drawings, it will be noted that as the upper and lower die members approach one another the rolled upper lip 213 initially engages the cam surface 60 of the button Sii. While the slope of the cam surface may vary according to use, it has been found that a slope which makes an angle with an exemplary vertical lip of between 20 and 60 is quite workable. Continued closing movement ofthe die portions causes a component of force normal to the cam surface 60 to be directed against the curled lip 213, having the benecial result of initially bending the lip inwardly, even though through prior manufacturing processes, the lip may have a slightly outward bend.

Further closing of the die portions results in further bending of the upstanding lip. Reference to FIGURE 3A will indicate an intermediate position of the die portions, demonstrating the bending action of the buttons. Continued movement brings about the flattening of the upstanding lip against the peripheral edge of the cover 14 as indicated in FIGURE 3B. At this point, the action of the support member 42 causes the button 50 to retract into its bore 51.

As pointed out, the upper closure die member 4S is a two-piece arrangement comprising the support plate 48 and the die ring 47. Referring to FIGURE 4, the support member 4d and die ring 47 are biased apart by means of suitable springs 76 disposed in an appropriate spring retainer housing 72 tted into a counter-sunk bore 74 in the member 43. Shallow spring retaining bores 76 are provided in the upper face of the die ring 4'7.

As seen in FIGURE 4, the inner profile of the die ring is rabbeted, defining walls 78 and 30, respectively. Again reverting to the operative movement of the members, as these members continue to move closer to one another, the upward force of the supporting die ring 42 urges the bent over lip portion 218 into engagement with the lateral crimping wall 86 on the inner part of the die ring 47. The force is sufficient to move the die ring upwardly against the bias of the spring into engagement with the support member 43 (see FIGURE 3B). This force is also sufficient to cause a final crimping of the cover 14 between the lip 218 and the at portion 118. In this manner, perfect sealing closure of the container is achieved.

Again referring to FIGURE 4, which is a section taken along lines 4-4 of FlGURE l, at the corner of the container, it will be observed that no pre-bend plunger is provided in this area. It has been found that the problems solved by the pre-bend plungers do not occur in this particular area of the container, and the strength of the side walls 219 in this area, is such that proper closure is achieved as the upstanding wall 219 engages and is bent over against the surface 80 on the die ring 47.

From the foregoing description it will be apparent that the present invention provides a new and improved closure die with which metal foil containers of rectangular form may by invariably covered and sealed in a satisfactory manner and it will also be apparent that this closing and sealing action may be accomplished with container of the type including flat rectilinear side and end walls, each formed with outward anges defining a continuous Hat about said container upon which a cover is supported at its edges, said flat terminating in a bendable upstanding closure lip, comprising in combination, an upper die member, a lower die member adapted to support said container, and means for moving said die members together, said upper die member being provided with means projecting therefrom for initially engaging the closure lip of said container as said die members move toward one another to provide an initial inward bending thereof, and including closure means subsequently engaging said initially inwardly bent lip for completely closing and crimping said lips about the edges of the cover upon further movement of said die members.

2. A device as set forth in claim 1 wherein said prebend means comprises a plurality of cylindrical reciprocable plungers, disposed in Abores in said upper die member, and means in said bores for biasing said plungers in a direction toward said upstanding lip.

3. A device as set forth in claim 1 wherein said prebend means comprises a plurality of cylindrical reciprocable plungers, disposed in bores in said upper die member, and means in said bores for biasing said plungers in a direction toward said upstanding lip, and said closure means comprising a continuous lateral surface disposed adjacent said pre-bent lip and adapted to engage the seam to press it against said cover in sealing relation.

4. The combination with a closure die structure for closing a container of the type having iiat rectilinear side and end walls and formed with outward flanges defining a continuous peripheral flat upon which a cover is supported, said flat terminating in a bendable upstanding closure lip, and including an upper die member having a rabbeted groove therein vertically aligned with said lip, a lower die member adapted to support said container by said peripheral fiat, and means for moving said die members together, of a plurality of reciprocable pre-bend plungers mounted at spaced points in said groove about said upper die member, each having a cam surface for engaging the edge of said lip for imparting an initial inward bend thereto.

5. The combination with a closure die structure for closing a container of the type having iiat rectilinear side and end walls formed with outward flanges defining a continuous peripheral at upon which a cover is supported, said flat terminating in a bendable upstanding closure lip and including an upper die member having a rabbeted groove therein vertically aligned with said lip, a lower die member adapted to support said container by said peripheral flat, and means for moving said die members together, of a plurality of spring lbiased reciprocable pre-bend plungers mounted at spaced points in said groove about said upper die member, each having a cam surface for engaging the edge of said lip for imparting an initial inward bend thereto,

6. The combination with a closure die structure for closing a container of the type having flat rectilinear side and end walls formed with outward flanges defining a continuous peripheral flat upon which a cover is supl ported, said flat terminating in a bendable upstanding closure lip and including an upper die member having a rabbeted groove-therein vertically aligned with said lip, a lower die member adapted to support said container by said peripheral flat, and means for moving said die members together, of a plurality vertically aligned recesses, a reciprocable pre-bend plunger disposed in each said recess, disposed in spaced relation in said groove about said upper die member, each having a cam surface for engaging the edge of said lip for imparting an initial inward bend thereto and means biasing said plungers toward said lip.

7. A closure die structure for closing and sealing a container of the type including flat rectilinear side and end walls formed with outward flanges defining a continuous peripheral flat about said container upon which a cover is supported, said flat terminating in a bendable upstanding closure lip, comprising in combination, and upper die member, a lower supporting die member adapted to support said container, and means for moving said die mem-bers together, said upper die member delining a plurality of recesses, spring biased plungers reciprocably disposed in said recesses and adapted to engage the closure lip of said container as said die members move toward one another to provide an initial inward bending thereof, and a lateral closure surface for closing and crimping said pre-bent lip about the edge of the cover upon further movement of said die members.

8. The combination as set forth in claim 4 wherein the cam surface deues an angle with the substantially vertical upstanding lip of between 15 to 75.

9. A closure die structure for closing a container of the type having flat rectilinear side and end walls formed with outward flanges defining a continuous peripheral flat upon which a cover is supported, said at terminating in la -bendable upstanding closure lip, the combination including an upper die member dening a rabbeted groove therein and a plurality of reciprocable pre-bend plungers mounted at spaced points in said groove about said upper die member, each having a cam surface for engaging the edge of said side and end lips for imparting a preliminary inward bending movement thereto.

10. The combination as set forth in claim 9 wherein said plungers are spaced so as to provide at least two opposite each side and end wall of said container.

References Cited UNITED STATES PATENTS 2,767,537 10/ 1956 Prince et al 53-366 2,886,933 5/1959 Hennies 53-366 TRAVIS S. MCGEHEE, Primary Examiner. FRANK E. BAILEY, Examiner. R. L. FARRIS, Assistant Examiner. 

1. A CLOSURE DIE STRUCTURE FOR CLOSING AND SEALING A CONTAINER OF THE TYPE INCLUDING FLAT RECTILINEAR SIDE AND END WALLS, EACH FORMED WITH OUTWARD FLANGES DEFINING A CONTINUOUS FLAT ABOUT SAID CONTAINER UPON WHICH A COVER IS SUPPORTED AT ITS EDGES, SAID FLAT TERMINATING IN A BENDABLE UPSTANDING CLOSURE LIP, COMPRISING IN COMBINATION, AN UPPER DIE MEMBER, A LOWER DIE MEMBER ADAPTED TO SUPPORT SAID CONTAINER, AND MEANS FOR MOVING SAID DIE MEMBERS TOGETHER, SAID UPPER DIE MEMBER BEING PROVIDED WITH MEANS PROJECTING THEREFROM FOR INITIALLY ENGAGING THE CLOSURE LIP OF SAID CONTAINER AS SAID DIE MEMBERS MOVE TOWARD ONE ANOTHER TO PROVIDE AN INITIAL INWARD BENDING THEREOF, AND INCLUDING CLOSURE MEANS SUBSEQUENTLY ENGAGING SAID INITIALLY INWARDLY BENT LIP FOR COMPLETELY CLOSING AND CRIMPING SAID LIPS ABOUT THE EDGES OF THE COVER UPON FURTHER MOVEMENT OF SAID DIE MEMBERS. 